Fix regex match group handling after moving to case statements

The rubocop autocorrect for Style/CaseLikeIf does not take into
account the match operator for regex, which in this case
returns the matched data when using it with and if/elsif statement.
After just moving this to an case statement, the data is not returned
anymore.
This could be fixed by using the `$LAST_MATCH_INFO` pseudo variable which
contains the whole `MatchData` object of the latest regex matching group.